Photosensitive system



United St tes Patent 2,829,052 Patented Apr. 1, 1 958 z,sz9,052 rnorosnmslrrvn SYSTEM "Lyman Chalkley, Washington, D. C.

Application November 16, 1955 Serial No. 547,338' r v r i Claims. (CL 96-90) N5 Drawing.

type of hydrocolloid and obtain these same advantages. Thus, it is a primary object of the present invention to provide a solid composition including a triphenylnietliane volatile and solid organic material ,so as" to be sensitive to ultra-violetilight.

* A further obje'ct of the invention is to provided photo- 'sensitivecomposition-capable of forming films which may befeither self sustaining or coated over a suitable supporting base and which are printing out materials of execeptionally high speed andlresolution.

Another object of the invention is to provide a photosensitive'combinationon which images printed by means iofultra violet ijrra diation are,permanentarid do not fade the dark, and "retain their finefdetail indefinitely. p Stillanbther'object of the invei tion isjto provide an activated triphenylrnethane dye cyanide composition sendi ffusioni of the activator.

it sitive to ultrawiolet light from which there will be no Yet another object at the invention is to i-sviaean Qactivated triphenylrnethane dye cyanide composition sensitive to ultra-violet'which is less subject to injury by contact with various deleterious" substances suchlas' resin in sized'papers' and phthalates in plasticized plastics.

Another object of the invention is to provide a pherochemical process which utilizes a composition which accomplishes the foregoing objects;

Other and further objects of the invention wit-rte appatent fiomklie fol'owing detailedidescription.

"iha've foundthat the collagenous proteins fdrm with the class ofth'e simple basic triphenylmethane dye cyanides,combinations' or compounds sensitive to ultra-violet and shorter wave lengths. This particular class isthe tri-prirnaryarnino triphenylacetonitr'iles and the compounds represented by the general formula lym ,ITIH: NHi

in which R, R and R are each a hydrogen atom or a methyl group, are all suitable for use in the present invention, singly or in admixture. 7

Of the four compounds embraced within this formula, 4,4',4" triamino triphenylacetonitrile and its 3-methyl derivative are preferred because of their ready availability, but the 3,3 dimethyl derivative and 3 ,3',3" trimethyl derivative also form quite satisfactory photosensitive combinations with collagenous proteinsx The photosensitive combination or compound formed between the collagenous proteins and the simple, hydrophobic, basic dye cyanides appears to be specific to the primary arnono substituted triphenylacetonitriles; It is not formedto any practical extent by the completely a1- kylated derivatives such as 4, 4',4" tris dimethylaminotriphenylac'etonitrile, or 4,4 bis dimethyl aminotriphenylacetonitrile.

Suitable collagenous proteins for use in the invention are the gelatines obtainedfrom calfskin, pigskin, hooves,

. I and the like and the glues, such as fish glues and the anidye cyanideof long shelf life whichis activated by a non-- mal glues obtained from hides and hooves. The individual gelatines and glues may difier considerably in their photosensitive combinations withthe indicated dye'cyan ides. a

'The nature of the combination of the dye cyanide with the collagenous protein has not been clearly established;

but the combination has some of the properties of a dyed material. For example, if a film formed of gelatine combined with one of the triprimaryamino-triphenylacetonitriles is soaked in cold waten'it swells and forms swollen 1 flakes of clear colorless gelatine. If the mixture is centrifuged and exposed to ultra-violet radiation the gelatine flakes become strongly colored while the aqueous layer remains colorless, showing that the dye cyanideds'still in activated combination .with the gelatine' andhas not been precipitated and deactivated by the addition of water.

t The method of combining-the dye cyanide with the collagen material is not critical as it is only necessary that the dye cyanide 'be brought into intimate contact therewith so that a photosensitive combination results. Thus the collagen material maybe in solid or liquified form during the formation of-the-photo-sensitive combination and one method employing the collagen derivative as a so'lid' delineates the analogy between the combination and a dyed material. Gelat'uie in its granular form of cornmerce may be stirred in a solution of dye cyanide salt cooled to a temperature (e. g. 0 C.) which prevents" dissolution of the gelatine, separated from the solution and washed with cold water. The gelatine may then be liquified by heating with the desired amount of water and used as coating material to yield smooth and colorless films which are sensitive to ultra-violet and shorter wave lengths. It will be apparent that the gelatine has extracted the dye cyanide from solution much astextiles will ex:

tract dyes in the processing of dyeing.

Another convenient method of forming the photosensitive combination is to mix an aqueous solution of the collagenous protein at a temperature at which it is liquid with a solution of the basic dye cyanidejin an organic solvent, such asi-propyl alcoholor acetonitrile, which is tolerated in considerable proportions by the collagen solution without precipitation of the collagn'. The resulting mixture may then be used to coat or iii!- pregnate a suitable base material and the solvent evaporated. The resulting dry product is-strongly sensitive to ultra-violet andshorter wave lengths to produce a magenta color. 7 I

One particularly advantageous method of forming the present photosensitive combinations makes use of the increased solubility in waterand hydrophilic organic solvents of the salts of the basic dye cyanides which are suitable for use in the present invention, thus facilitating their admixture with a solution of the collagenous protein. In accordance with this process, an aqueous solution of the collagenous protein at an elevated temperature is mixed with a solution of a salt of the dye cyanide.

The use of acid in this method has the added advantage that the presence of acid in addition to the basic dye cyanide and collagenous protein leads in general to more sensitive preparations than the combination of collagenous protein and dye cyanide in the form of its base alone. I have found it generally satisfactory to employ acid in the ratio of one equivalent to three equivalents of acid per molecule of dye cyanide. The use of less acid does not provide the advantages sought; whereas'the use of more than three equivalents of acid per molecule of dye cyanide, although it does not prevent the formation of a photosensitive film, results in unnecessary degradation of the protein and gives. a prodnot that is inferior in physical qualities.

The acid employed may be a mineral acid or an organic acid, it being only necessary that the acid belong to the group referred to as strong acids. That is to say, the acid should have a dissociation constant for the first hydrogen greater than l As examples of such acids there may be named hydrochloric, sulfuric, perchloric, dichloracetic, trichloracetic, benzene sulfonic, p-toluene sulfonic, formic and oxalic.

While it is preferred that the acid be introduced into the photosensitive combination in the form of a salt of the dye cyanide, it is to be understood that it can be added in any other suitable manner.

Regardless of the method of forming the photosensitive combination, its solutions lend themselves excellently to the preparation of coated and impregnated materials which have a number of important uses, for example, coated glass plates may be used for the preparation of lantern slides and other transparencies which can be projected or examined by visible light without any, fixing process and without destroying the ultraviolet photosensitivity; Likewise, cellulose acetate and, similar films may be coated'to make transparent photosensitive materials.

Papers may also be coated, and, for example, Baryta coated photographic raw stock, when coated with a.film of the composition of this invention affords an opaque photosensitive sheet that prints rapidly to give a brilliant image.

The collagenous protein-triaminotriphenylacetonitrile combination is capable of giving films of extremely high resolution so that images will show microscopic detail. These films have no grain like a silver emulsion, and are transparent and uniform under a microscope. The

images formed have the property of being as sharp as the beam of light producing the image. Where the image is projected by a lens or other focusing device, maximum resolution is obtained by making the photosensitive film very thin so that it may be placed at the exact focus at which the image is formed and thus hold to a minimum the sidewise diffusion of the image as the light passes through the film.

The relative proportion of dye cyanide to collagenous protein in the photosensitive combination is not critical and must necessarily vary widely in accordance With such factors as the viscosity of the protein solution employed in preparing the combination and the thickness of the dried films to be formed therefrom. In general, the

amount of dye cyanide should be kept as low as possible consonant with the formation of clear, deeply-colored images. In most instances, the proportion of dye cyanide will fall within the range of 0.1 to 10.0% based on the weight of the dried photosensitive combination. 7

Expressing the amount of dye cyanide in terms of the exposable surface area of the photosensitive product, it

has been found that there may be from .01 to 10 mgms. of dye cyanide per square inch of surface.

The following examples are set forth as being illustrative of, but not as limiting, the invention.

Example 1 One volume of a 10% aqueous solution of purified calfskin gelatine is mixed at 45 C. with V2 volume of a A of 1% solution of 4,4,4"-triamino-triphenylacetonitrile in acetonitrile. The resulting mixture is poured onto level glass plates which are dried in the dark in a dust free atmosphere. Exposure of the dried film to 10,000 ergs per square centimeter of 2537 A.

radiation prints out a good magenta image which has good resolution and does not fade in the dark.

Example 2 One gram of 4,4',4"-triamino-triphenylacetonitrile is dissolved at room temperature in 9.6 ml. of normal hydrochloric acid and the solution diluted to 100 ml. with water, to give approximately 1% dye cyanide dissolved as the trihydrochloride. A sensitizing mixture is made of 10 ml. of the above solution, ml. of water, m1. of 10% gelatine and 30 ml. of 91% i-propyl alcohol, all at 50 C. The mixture is cooled to C. and used to impregnate 24 lb. water leaf paper, which is air dried in the dark. This paper gives usable images over the exposure range of 2,000 to 1,000,000 ergs per square cm. of total radiation of wave lengths 3132 A. and shorter from a hot quartz mercury lamp.

Example 3 10 ml. of the approximately 1% dye cyanide solution as trihydrochloride prepared in Example 2 is mixed with 30 ml. of water and 20 ml. of photo-engraver's glue (e. g. Rogers Photoengravers Glue). Water leaf paper is impregnated with this mixture and dried in the dark to give a material sensitive to radiation shorter than 3250 A. The sensitizing mixture may also be applied to paper or cloth with a brush through a stencil to give photosensitive designs.

Example 4 Twenty-five grams of Magenta ABN (General Dyestuffs Corp.) is dissolved in 350 ml. of boiling water, the

solution cooled to C., filtered, and the filtrate treated with a solution of 5.3 g. of 95% sodium cyanide in 25 ml. of water. Reaction begins immediately with precipitation of the new compound. The reaction mixture is allowed to stand in the dark at room temperature for 12 hours, and the following operations carried out by yellow light. The reaction product that has precipitated is collected on a filter, washed on the filter with 1000 ml. of water, and air dried at C.

Purification is carried out as follows: Ten grams of the dry crude product is dissolved by stirring at 25 C. 'in a mixture of ml. of triethyl phosphate and 25 ml. of water. The solution is filtered and put in a 400 ml. beaker and stirred while water is added drop 'by drop at the rate of 2 ml. per hour until a total of ml. of water has been added. The nearly colorless crystalline precipitate of 4,4,4"-triamino-3,3',3"-trimethyl-triphenylacetonitrile is collected on a filter, washed with water until the wash is colorless, and dried in a vacuum desiccator over sulfuric acid. A second crop of slightly less pure material may be obtained by treatment of the mother liquor with 700 ml. more water added all at once.

A solution of 0.05 g. of 4,4,4"-triamino-3,3',3"- trimethyl-triphenylacetonitrile in 4 ml. of boiling acetonitrile is cooled to 50 C. and added with stirring to 34 ml. of 10% aqueous gelatine solution at the same temperature. Twenty-four pound filter paper is impregnated with this solution by being dipped in it, and is air dried. The resulting colorless paper turns pink on exposure to ultra-violet.

- to 200 ml. and cooled to C.

, In yellowlight 0.6 tonitrile is dissolved by stirring at room temperature in 5.7 ml. of normal hydrochloric acid and the solution made up To this solution is added 480 ml., 1 of i-propyl alcohol and 10 g. of granular U. 8.1. gelatine; and the mixture is stirred at 20 C. for 9 hours. Thegelatine is then allowed to settle.

Ex mple A solution ofrosan iline cyanide mono-"p -t'oluene suli solved the solution is cooled to 50 C. andfmixed by stirring with a solution at the same temperature of- 5 g.

of gelatine in 85 ml. of water. i The resulting mixture is coated onto glass plates, using V2 ml. per square inch- 1 of surface, which are dried inthe dark. The resulting film prints out a magentaimage'jon' exposureto ultraviolet. i

Example 6 At room temperature 0. 3 g. of 4,4,4"-triamino-triphenylacetonitrile is dissolved in 2.85 ml. of normal bydrochloric acid by stirring for a few hours in the dark or yellow light. out by yellow light. The solution is diluted with water grams of granular U. S. P. gelatineis added and the mixture stirred at 0 C. for 1 /2 hours. The mixture is then made up to a volume of 500 ml. with ice water, allowed to settle for minutes, and the supernatant cloudy solution decanted from the gelatine, which is washed three times in the same way with 500 ml. portions of ice water. When the last wash has been decanted the gelatine suspension, which has a volume of about 150 ml. is liquified 'by heating to 100 C. in a water bathand used to coat glass plates with 2 ml. per square inch of surface. The dried filmsrare colorless and smooth, though with a slight grain, and be:-

come magenta on exposure to ultra-violet radiation of wave length shorter than 3300 A.

Example 7 t g. of 4,4',4"-triaminotriphenylaceto 180 ml. of water.

The clear supernatant solution is decanted and the gelatine washed twice with' 100 ml. portions of i-propyl alcohol. Water is then added to the drained gelatine to a total volume of 150 ml. The gelatine is liquified by heating the mixture to 100 C. in

a water bath, and glass plates are coated, using 2 ml. of solution per square inch of glass surface. colorless and completely clear, and prints grainless images on exposure to ultra-violet.

Example 8 By yellow light, 0.3 g. of 4,424f-triamino-3-methyl-triphenylacetonitrile and 0.175 g. of p-toluene sulfonic acid mono-hydrate are dissolved in 30 mljof boiling i-propyl alcohol, the resulting clear solution cooled and made up to 40 ml. with water. At C. 5 g. of granular U. S. P. gelatine is added and the mixture stirred at this temperature for 2 hours. The gelatine is allowed to settle, the supernatant solution decanted, and the gelatine washed twice with 100 ml. portions of i-propyl alcohol. The drained gelatine is made up to 75 ml. with water, dissolved by heating to 100 C. on a water bath and used to coat barium sulfate coated paper. Thedry coated paper prints out a magenta image on exposure to ultra-violet.

In the above preparations all solutions containing a triaminotriphenylacetonitrile, and its combinations with a collagenous protein, should be protected from ultraviolet radiation and handled preferably by yellow light such as is suitable for the processing of silver developing out paper.

The. film dries" The rest of the preparation is also carried violet and shorter wave lengths, consisting of a combination of a collagenous protein and a triprimaryamino-triphenylacetonitrile.

2. A solid composition photosensitive only to ultra violet and shorter wave lengths, consisting of a combina- 7 tion of a collagenousprotein and a colorless dyecyanide having the general formula N H2 N H: 7 NH:

I CN

claim 2 which 'acetonitrile.

7. Asolid' composition photosensitive only to ultraviolet and shorter wave lengths, consisting of a combination of a collagenous protein, a colorless dye cyanide having the general formula V H2 H2 NH:

. O R1 R2 wherein R, R and R are each selected from the. group consisting of a hydrogen atom and a methyl group and 1 to 3 equivalents of an acid having a dissociation con stant for the first hydrogen greater than 10 for each molecule of said dye cyanide.

- 8. A product of manufacture comprising a base sheet coated with a solid composition photosensitive only to ultra-violet and shorter wave lengths,-said composition consisting of a combination of a collagenous protein and a colorless dye cyanide having the general formula wherein R, R and R -are each selected from the group consisting of a hydrogen atom and a methyl group;

9. The product of claim 8 in which said collagen material is a gelatine.

10. A productof manufacture comprising a base sheet coated with a solid composition photosensitive only to ultra-violet and shorter wave lengths, saidcomposition consisting of a combination of a collagenous protein, a

colorless dye cyanide having the general formula NH: IFTHz NH:

wherein R, R and R are each selected from the group consisting of a-hydrogen atom and a' methyl-groupand 1' to 3 equivalents of an acid having a dissociation constant for the first hydrogen greater than 10, for each molecule of said dye cyanide. V v

11. A photochemical process comprising exposing to ultra violet light to produce a colored compound, a solid composition consisting of a combination of acollagen material and a colorless dye cyanide having the general formula N112 N H2 NH:

I CN sisting of a hydrogen atom and a methyl group.

12. The photosensitive composition of claim 7 in which said dye cyanide is 4, 4', 4"-triamino-triphenylacetonitrile. 1:3, Thephotosensitive composition'of 'claim7 in which said dyecyanide is 4, ,4, 4-triamino-3-methyl-triphenyl acetonitrile.

14. The photosensitive composition of claim 7 in which said dye cyanide is 4,4,4"-triamino-3,3,3-trimethyltriphenylacetonitrile.

15 The, photosensitive composition of claim 2 in which said, dye cyanide is 4,4,4"-triamino-3,3',3"-trimethyltriphenylacetonitrile.

- References Cited in the file of this patent UNITED STATES PATENTS 1,845,835 Frankenburger et a1 Feb. 16, 1932 2,213,745 Schinzel Sept. 3, 1940 2,528,496 Chalkley Nov. 7, 1950 2,730,457 Green et a1. Jan. 10, 1956 

1. A SOLID COMPOSITION PHOTOSENSITIVE ONLY TO ULTRAVIOLET AND SHORTER WAVE LENGTHS, CONSISTING OF A COMBINATION OF A COLLAGENOUS PROTEIN AND A TRIPRIMARYAMINO-TRIPHENYLACETONITRILE. 